Method of treating armor or deck plates.



UNITED STATES PATENT OFFICE.

SAMUEL S. WALES, OF MUNIIALL, PENNSYLVANIA, ASSIGNOR TO CARNEGIE STEEL OOMPAN Y, OF PITISBURG, PENNSYLVANIA, A CORPORATION OF NEW JERSEY.

METHOD OF TREATING ABMOR OB DECK PLATES.

Specification of Letters Patent Patented May 18, 1909-.

Application flied July 13, 1907. Serial No. 383,689.

' 0 all whom it may concern:

Be it known that I, Samrm. S. WALns, of Muuhall, Alleghenycounty, Pennsylvania have invented a new and useful Method of Treating Armor or Deck Plates, of which the following is a specification.

Of recent years it has been the practice in the manufacture of armor plate to make the plate of steel having substantially the following theoretical composition Carl) .28 per cent. Manganese H .35 per cent. Nickel 3.75 per cent. hromium 1.70 per cent.

the sulfur and silicon being low,bel0w .04- per cent. The steel of this composition is then treated by the Harvey or Krupp processes by which its surface is highly supercarburized for the purpose of rendering it more resistant to the impact of projectiles.

I have discovered a new alloy or composition and a new mode of heat treatment b which I am enabled to increase the ballistic resistance over that obtained by the alloys and treatments heretofore in use.

The elements which I alloy with the iron in order to produce my new composition are as follows. and in stating them I desire to premise that in addition to these elements others may be added if desired or the. proportions may he varied within certain limits, those which l give being such as I have found host suited to the purpose (larbon .20 to .30 per cent. Manganesel .25 to 4 per cent. hromium 1.25 to 1.75 per cent. Vanadium .10 to .25 per cent. Nickel 3.50 to 4 per cent.

The steel which I employ is preferably opt-n hearth steel. and I prefer to add the nickel as a part of the charge of the furnace in a cold condition. 1 preferably preheat the chromium and add it to the open hearth charge just before trapping. The manganese is preferably added cold in the ladle and the vanadium is preferably added to the ladle in the form of preheated ferro-vanadium alloy. These alloys may however be added in a molten form in the ladle or otherwise as desired. The proper portion of carbon may be added-by recarburizing by the usual methods. The silicon contents of the steel should be low, less than .15 per cent. The sulfur should be as low as possible, preferably less than ,04 per cent. It is extremely important in this vanadium alloy that the phosphorus should be extremely low because the vanadium is found to intensify the action of this element. The phosphorus should not exceed .04 per cent.

Having cast the in ct, it may be forged or rolled to the desire thickness. It is then raised to a temperature of about 700 degrees C. and allowed to become cold slowly, preferably in air; or it may be annealed by bedding in lime or ashes. If the processes are to be continuous, the intermediate annealin may be omitted. The plate is then heate above 875 degrees C. and referably about 900 degrees C. and queue ied with water until it is either at the temperature of the atmosphere or at a temperature of not over 400 degrees. I then preferably anneal the plate by raisin to a. temperature above 350 degrees C. anc below 700 degrees (3., depending upon the purpose for which the plate is to be used; and cool the same slowly, preferably in air. The lower the temperature of the last or third heat treatment, the harder and less ductile the material will be. By taking the plate after the third treatment and again raising it to about. 900 de grees O. watcr-qucnching it, and reanneah ing it. tho pinto may be further toughened. By simply repeating the third heattreatinrnt, or annealing step, the plate may be rendered more ductile. The plate will be given a fibrous character by the preceding treatment, including the heat treatment of 700 degrees and following anncalings. This fibrous character. however, may be imparted in any desirable or well known manner.

The advantages of my invention result from the increased ballistic value, since the plates thus obtained are capable of resisting shocks to a greater extent than ordinary steel plates. Another great advantage of the product thus obtained is that it may be machined by ordinary tools in finished condition or after its final metallurgical treat ment. Another advantage is that the fibrous character which is imparted to the plate during certain stages of the treatment is retained through the subsequent steps of i reatment.

Those skilled in the art will be able to modify the steps of the heat treatment within certain limits, Without departing from my invention.

I claim 1. The method of making armor or deck plates, consisting in preparing a steel plate containing vanadium, imparting a fibrous character to the plate by heat treatment, then hardening the plate by raisin it to a higher temperature than that em oyed in fiberin and then annealing the p ate; substantia ly as described.

2. The method of making armor or deck plates, consisting in preparlng a steel plate containing vanadium, imparting a fibrous character to the plate by heat treatment, then raising the plate to a temperature above 875 degrees 0., suddenly cooling it and then annealing the plate; substantially as described. g 3. The method of making armor or deck plates, consisting in preparmg a steel plate containing vanadium, imparting a fibrous character to the plate by heat treatment,

uznuzo then raising the plate to a temperature above 875 degrees (3., suddenly cooling it, and then annealing it by raisin it to a temperature above 350 degrees and elow 700 degrees C., and cooling 1t slowly; substantially as described.

4-. The method of making armor or deck plates, consisting in preparing a steel late containing below one per cent. of vana ium, imparting a fibrous character to the plate by heat treatment, then raising the late to a temperature above 875 degrees denly cooling it, and then annealing it by raising it to a temperature above 350 degrees and below 700 degrees 0., and cooling it slowly; substantially as described.

In testimony whereof, I have hereunto set my hand.

SAMUEL S. WALES.

\Vitnesses I JOHN MILLER,

H. M. Conwm.

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